This core has two functions and serves all four Projects: 1. Central Facility: This section of the Core is for maintenance, record keeping, and procurement of animals for the four projects. The Core will maintain all surgical records. The personnel associated with the Core will perform ordering, shipping and handling of the rats and transgenic mice. Personnel employed by the Biologic Resources Laboratory (BRL) will be responsible for feeding, watering, and cage cleaning (per diem costs included in budget, see Table 1). Any post-operative complications resulting from the animal surgeries will be addressed by consultation of Core personnel with the veterinary staff at the BRL. Data obtained from the physiological and echocardiographic measurements of the animals will be analyzed and summarized by the Core personnel and presented to the individual project principal investigators. 2. Animal Model and Cardiac Analysis Facility: This section of the core will provide surgical models of transverse aortic banding (pressure overload), aorta-cava fistula (volume overload), and coronary artery ligation (myocardial infarction) in rats, and transverse aortic banding in mice. Core personnel will also instrument rats and mice for measurements of left ventricular hemodynamics using a Millar pressure/volume catheter. Pressure/volume curves will be constructed under baseline conditions and subsequent to inotropic challenges with beta- and alpha-adrenergic agonists. The Core will also perform 2-dimensional and M-mode echocardiography and Doppler aortic and pulmonary flows on mice and rats, before and after surgery, to demonstrate changes with cardiac remodeling and confirm any changes in contractile performance of the heart as assessed by pressure/volume measurements.